Digital networks have been developed to facilitate the transfer of information, including data and programs, among digital computer systems and other digital devices. A variety of types of networks have been developed and implemented using diverse information transfer methodologies. In some networks, such as the well-known Ethernet, a single wire is used to interconnect all of the devices connected to the network. While this simplifies wiring of the network in a facility and connection of the devices to the network, it results in generally slow information transfer, since the wire can only carry information, in the form of messages, from a single device at a time. To alleviate this to some extent, in some Ethernet installations, the network is divided into a number of sub-networks, each having a separate wire, with interfaces interconnecting the wires. In such installations, wires can carry messages for devices connected thereto simultaneously, which increases the number of messages that can be transferred simultaneously. It is only when a device connected to one wire needs to send a message to a device connected to another wire that wires in two or more sub-networks will be used, making them unavailable for use by other devices connected thereto.
To further alleviate this, networks have been developed in which communications are handled through a mesh of switching nodes. The computer systems and other devices are connected to various switching nodes. Since the switching nodes themselves are interconnected in a variety of patterns, a number of paths may be available between pairs of the devices, so that if one path is congested, another may be used. Such an arrangement may result in a network which is more complicated than an Ethernet network, but it can provide substantially higher information transfer rates, particularly if optical fiber is used as the media interconnecting the switching nodes and devices. A problem which may arise with such networks is that, in such networks, a switching node or a device, when it is receiving information from another switching node or device in the network, does not have a mechanism to provide “flow-control” information to the transmitting switching node or device. While this does reduce the cost of a network, it may result in congestion, in which either a switching node may receive information at a rate faster than it can transmit it, or a destination device may receive information at a rate faster than it can buffer and process it.